Interleukin-2 (IL-2) is a potent cytokine that acts on the immune system to generate primarily a cell-mediated immune response. Under the appropriate conditions, IL-2 is produced locally at high concentrations near the site of an antigen in order to supply the necessary co-stimulatory signals for generating an immune response to the antigen. Because of its role in the growth and differentiation of T cells, IL-2 has been a candidate in immunotherapeutic approaches to treating tumors. In addition to stimulating T cells, IL-2 has also been shown to stimulate B cells, NK cells, lymphokine activated killer cells (LAK), monocytes, macrophages and dendritic cells.
IL-2 is an approved therapeutic agent for the treatment of metastatic renal carcinoma and metastatic melanoma but its use is restricted due to severe toxic side effects, which include fever, nausea, vascular leakage and hypotension. Among the various toxic effects observed with IL-2 administration, the one toxic effect that is the least desirable and is believed to substantially interfere with IL-2 therapy is vascular leak syndrome (VLS) and the complications associated with it.
Therefore, there remains a need in the art to further enhance the therapeutic usefulness of IL-2 proteins.